Topic 1 · pp. 32–37 · Free
Topic Notes · Easy summaries with diagrams
Chapter 16 — Chapter 16 — Electrochemistry
0 of 6 steps done ✓ (5 topics + Exercise)
Topic 1 of 5
📘Easy summary
Rules: free element = 0; monatomic ion = its charge; O = −2 (peroxides −1); H = +1 (metal hydrides −1); group 1 = +1, group 2 = +2; sum in neutral compound = 0, in ion = charge. E.g., Mn in K₂MnO₄: 2 + x − 8 = 0 → +6; Cl in Ca(ClO₃)₂: 2 + 2x − 12 = 0 → +5. Ionic formulae: write ions, cross over charges to make total zero: Al³⁺ + O²⁻ → Al₂O₃; NaOCl, CaC₂O₄, (NH₄)₃PO₄, Ca(NO₂)₂.
⭐Key points
- Use brackets for polyatomic ions taken more than once.
🔬Diagram
🌿Real-life example
S in Na₂S₂O₃ = +2.
💡Exam tip
- Show working with x.
✅Quick check
1. Mn in K₂MnO₄:
2. Cl in Ca(ClO₃)₂:
Practice this chapter
Lock it in with flashcards and exam-style MCQs.